Unless otherwise indicated herein, the description in this section is not prior art to the claims in this application and is not admitted to be prior art by inclusion in this section.
An image forming apparatus, which is a printer, a multifunction printer, or a multifunction peripheral, can transmit image data of a read document to a portable terminal such as a mobile phone, a smart phone, and a tablet terminal via wireless communication. The portable terminal can receive the image data from the image forming apparatus and display the image data on an operation panel of the portable terminal. For example, in one output processing program and output device (e.g. portable terminal), an output device such as a mobile phone displays the image of image data received from an image-data acquiring apparatus (e.g. image forming apparatus) on a panel of the output device. The operation for page turning for the image displayed on the panel of the output device can be achieved by the operation where a user tilts the output device with one hand. That is, when the user tilts the portable terminal, the page turning can be performed with respect to the image displayed on the panel of the portable terminal corresponding to the rotation direction of the tilting.